This invention relates to door operating devices, i.e., so-called automatic door operators or actuators. More particularly, it relates to an electrically actuated door operator incorporating certain new and highly useful improvements in motion transmission systems.
In the automatic door industry, which now serves a market of world-wide scope, there has been a continuing need and effort to provide technologically innovative, more reliable, more long-lasting, quieter, more compact, more economical door operators. Because such operators must be used in a limited space of door structures for providing operation of doors strictly in accordance with specifications, and are expected or hoped to be able do so reliably for year after year, the designer must meet size and operating contraints which do not permit variation significantly from given size or operational limitations or to adopt wholly new types of movements or functions.
Rather, the designer must be able to conform a door operator to these limitations. In doing so, the designer must confront the design with a recognition of having available only a limited number of possible parameters and components which can be varied or designed to provide a superior operator design with capability of meeting specifications and satisfying ever-changing needs of the marketplace for lower cost coupled with greater longevity and better performance than existing technology.
As every door operator accordingly must include a prime mover and some sort of drive mechanism for coupling door-actuating energy from the prime mover to the door to be actuated, appliction of highly disciplined, experience-oriented design of the drive mechanism will be understood to be of paramount significance, with the most critical attention to the preselection of design philosophies and component elements, testing, and elimination of any potential for an "Achilles' heel" in a product which, once fielded, is expected to perform faultlessly, smoothly and quietly (which is to say unobtrusively) for years on end, if possible.
It has been determined that certain advantages accrue from a drive mechamism in which gearing is used to couple power from an electric motor, as the archetypical prime mover, to a door operating shaft. There are many transmission gear drive mechanisms in the prior art of door operators.
My U.S. Pat. No. 4,333,270 illustrates a door operator wherein the design included a transmission for speed reduction having a series of bevel gears with mutually perpendicular axes to drive a final pinion parallel with, and driving, the door shaft. The transmission similarly is of greater length than I now believe possible or desirable.
My U.S. Pat. No. 3,422,704 describes an automatic door operator in which I brought about a 90.degree. relationship between the motor and door axes by using a bevel gear arrangement for rotating the door shaft, employing two simple, independent planetary gear structures in series between the motor and bevel bears for speed reduction. These planetary gear structures and a clutch mechanism provided far greater length of the overall mechanism than I now would prefer.
Other prior art gear train speed reduction mechanisms may be noted.
U.S. Pat. No. 3,457,674 although disclosing intermeshing bevel gears for 90.degree. angle drive, shows a power transmission between the motor and bevel gears which employs a drive referred to by the trade designation "HARMONIC DRIVE." This drive mechanism, while compact, has certain inherent design limitations not suited for achieving the intended power-handling capability, reliability, compactness and performance of the present operator.
For example, U.S. Pat. No. 4,045,914 describes an operator with a four-gear speed reduction train including a ring gear carried on a shaft which latter mounts a bevel driven gear meshing with a bevel gear secured on the door driving shaft to bring about a 90.degree. angle relationship between the axes of rotation of the driving motor and door shaft. A six-gear train of relative complexity provides for motion transmission, with speed reduction accordingly, to the bevel driving gear. A difficulty of this approach, as with comparable others of the prior art, is that a final bevel drive gear and the transmission housing is exposed to high stresses with correspondingly high wear both on the teeth and associated bearings
Consequently, it is seen that there are problems with prior art door operators, such as objectionable size, too great an operating noise, high wear, and high stress, and even proneness to early failure, which not only need to be overcome but can be overcome by an operator of the present invention.
In addition to the need for obviating these problems and that of providing the 90.degree. angle drive relationship noted, a door operator desirably also must be capable of reconfiguration to meet a wide variety of different possible door installations, where the door may swing in only one direction, or the other, or may instead be needed to swing in both directions, be powered in only one or both directions, be capable of so-called break-away operation for safety reasons, and so forth. Such reconfiguration of the door operator for these different kinds of door installations should be facile and economic, without requiring wholly new or different mechanisms for each possible installation. Accordingly, the door operator should be universally adapable. It should also easily permit adjustments for precise variation in closing and opening limits of movement, as may be dictated by a specific installation.
My above-noted U.S. Pat. No. 4,333,270 illustrates use of a module of interchangeable character although in a door operator employing an intermeshed bevel gear for bringing about the above-described 90.degree. axial relationship, and a subsequent train of gears and pinions, with the difficulties of a relatively long transmission with a housing extending along the gear train.